In general, as coated tools, there are inserts which are detachably attached to the tip end portion of an insert holder to be used for turning or planing of a workpiece, such as various types of steels and cast iron, drills or miniature drills used for drilling or the like of a workpiece, and solid type end mills used for facing, grooving, shoulder milling, and the like of a workpiece. In addition, as coated tools, insert type end mills and the like are also known which include inserts detachably attached thereto and perform cutting in the same manner as solid type end mills.
Hitherto, as one of the coated tools, a coated tool is known which includes a hard coating layer having a plurality of layers formed by chemical vapor deposition (CVD), has a structure in which an outer layer is made of Ti1-xAlxN, Ti1-xAlxC, and/or Ti1-xAlxCN (0.65≦x≦0.9, preferably 0.7≦x≦0.9), the outer layer has a compressive stress between 100 MPa and 1100 MPa, and preferably, between 400 MPa and 800 MPa, and a TiCN layer or Al2O3 layer is disposed under the outer layer, and therefore exhibits excellent heat resistance and cycle fatigue strength (refer to PTL 1).
In addition, as one of the coated tools, a coated tool is known which includes a tool body, a wear-resistant layer formed on the tool body, and an outermost layer formed on the wear-resistant layer, in which the wear-resistant layer is made of a nitride, carbonitride, oxynitride, or oxycarbonitride of a first element and has a cubic crystal structure, and the first element is any one of (1) to (3):(TixAly) where 0.3≦x≦0.7, 0.3≦y≦0.7, x+y=1  (1)(TixAlySiz) where 0.3≦x≦0.7, 0.3≦y≦0.7, 0.05≦z≦0.2, x+y+z=1  (2)(TixSiz) where 0.8≦x≦0.95, 0.05≦z≦0.2, x+z=1  (3)
the outermost layer is made of a nitride, carbonitride, oxynitride, or oxycarbonitride of Al which is a second element, and has a hexagonal crystal structure, and
the coated tool satisfies conditions of:
(a) the total film thickness of the wear-resistant layer and the outermost layer is 0.5 μm to 15.0 μm, and
(b) the film thickness of the outermost layer is 0.1 μm to 5.0 μm (refer to PTL 2).
In addition, as another coated tool, a coated tool is known in which a hard coating layer made of (Al,Ti)N is vapor-deposited on the surface of a tool body made of a sintered tungsten carbide-based cemented carbide, the hard coating layer has a structure in which a thin layer A made of granular (Al,Ti)N crystals and a thin layer B made of columnar (Al,Ti)N crystals are alternately laminated, each of the thin layer A and the thin layer B has a layer thickness of 0.05 μm to 2 μm, the crystal grain size of the granular crystals is 30 nm or less, and the crystal grain size of the columnar crystals is 50 nm to 500 nm, and therefore excellent wear resistance to high-speed intermittent cutting of high hardness steel is exhibited (refer to PTL 3).